Waveform generators are used in function generators to control the generation of various output signals such as pulses, and ramps. The duration of these signals may be controlled by varying the duty cycle of a triangular waveform output by the waveform generator. Typically, the symmetry of the triangular waveform was varied to provide different signal durations. However, past techniques have the disadvantage that the frequency of the triangular waveform generated was affected when the symmetry was altered. This is because each leg of the triangular waveform was independently adjusted.
In the preferred embodiment of the present invention independent adjustment of the symmetry and frequency of the triangular waveform is provided. A signal produced by a tuning amplifier determines the frequency of the triangular waveform. A symmetry control circuit divides this signal into two control signals. Two voltage controlled current sources, responsive to the control signals are switched to alternately charge and discharge a capacitor to produce the triangular waveform.